Was awaken about 3:00am the other day with the Tahoe's alarm blaring. Turned it off, waited a few seconds, turned it on, back to bed. Few minutes later, blaring again. Did this one more time, and decided to turn off the alarm all together. The next day when I put it into gear I got a message that the drivers door was ajar, opened and closed. Still got the same message and the alarm beeped, but didn't stay on. Any ideas?

Also, the speedometer needle is pegged way past the last mph number.